1. Field of the Invention
The present disclosure generally relates to communication and recharging elements that are used for implantable electrical devices. More particularly, the present disclosure relates to an implantable lead having multiple charging and/or communication elements.
2. Description of the Related Art
There are a variety of implantable devices for which it is desirable to provide remote communication and electrical recharging. Such devices can include pacemakers, implantable drug delivery systems and nerve stimulation devices. Among the latter are implantable devices for nerve stimulation, such as vagus nerve stimulation (VNS). VNS has been used as a treatment for intractable epilepsy. VNS is achieved through an implanted pulse generator that delivers a bipolar, biphasic pulse to the vagus nerve. The implant procedure is very similar to the implantation of a pacemaker. The generator is implanted subcutaneously, typically in the upper left chest wall. An electric lead is connected between the pulse generator and one or more electrodes on the vagus nerve using a subcutaneous tunneling tool to the left vagus nerve, which lies in the carotid sheath.
Many implantable devices were originally designed with non-rechargeable batteries. More recently, however, rechargeable devices have been developed, allowing a user to periodically recharge the device using an inductive charging device that is magnetically coupled between the inductive recharging elements of the implanted device and an external recharger device having corresponding inductive elements. However, such recharging presents several challenges. In typical implantable devices, the inductive recharging elements of the implanted device are located in the body of the device itself, such as the pulse generator unit of the VNS system described above. Unfortunately, the depth of implantation of the device affects charging time and power usage because the casing of the implanted device and soft tissue between the device and the recharger have the effect of attenuating power transfer. Additionally, recharging takes time—typically several hours. Positioning the recharger in a specific orientation on the individual for an extended period of time can be difficult. It is desirable that the recharging elements of the implanted device are properly aligned with the recharger—for example, directly over the implanted device. However, the positioning of the recharger in a fixed location for an extended period of time can be a challenge due to varying body profiles (which can also change with time) and any movement of the individual. Furthermore, recharging can cause heating of the implanted device, potentially damaging surrounding tissue.
Similar challenges relate to communications with such devices. With many implantable devices, it can be desirable to provide programming commands, such as from a programmer or patient monitoring device, to adjust the device's operation. These commands can be transmitted to an antenna of the device using the medical information communication system (MICS). However, soft and fatty tissue between the antenna and the transmitter increase the power required for these transmissions.
It is desirable to provide safe, simple, and convenient recharging and communications with implanted devices. It is believed that many current implantable devices fall short in this area. The present disclosure is directed to overcoming, or at least reducing the effects, of one or more of the issues set forth above.